"The study of riparian vegetation is based on the observation of natural plant communities that spontaneously colonize areas newly exposed following the removal of the Vezins and La-Roche-Qui-Boit dams.

The vegetation monitoring program comprises two complementary approaches:

i) a vegetation sampling method based on floristic surveys (composition and structure) conducted within a series of plots positioned along a transect

ii) monitoring of Vegetation Units (VUs) observed within the valley

i) Sampling monitoring:

The sampling monitoring system is based on measurements distributed at different points in space (longitudinally and laterally). It aims to identify the diversity of flora and vegetation and describe the structure of emerging formations and plant communities within the neo-valley. Implemented annually (sub-annual only for 2021, before dismantling), this monitoring aims to identify and characterize the evolution trajectories of these vegetation over time.

The vegetation sampling protocol is implemented at several stations located along the course of the Sélune and at the mouth of several tributaries located in the right-of-way of the two former reservoirs. The sample of stations is supplemented by a batch of stations positioned outside the right-of-way of the two former reservoirs, downstream and upstream, which constitute so-called "reference" stations.

For each station, a transect is established perpendicular to the channel, from the bank to a reference point located at the level of the former water reservoir (i.e. 60m NGF for Vezins & 28.5m NGF for LRQB). Along this transect, 25m2 (5mx5m) quadrats are positioned according to previously set distance intervals. These quadrats (named Q1 to Q1+n) constitute the elementary unit within which abiotic (slope, texture...) and biotic (composition, structure) parameters are characterized and evaluated. The number of quadrats sampled per station varies depending on the width of the exposed bank (or transect length). It is completed by a reference quadrat, located beyond this maximum value (named Q0).

The inventory of vascular flora, i.e. herbaceous and woody plant species (excluding bryophytes) within quadrats aims at exhaustiveness and identification up to specific or even sub-specific rank.

ii) Monitoring of Vegetation Units:

The monitoring system for Vegetation Units is based on the identification of vegetation distributed along the transect at each station in the main stream. It aims to obtain a representative view of diversity and the organization of plant formations and communities.

This monitoring consists of identifying the discontinuities in terms of composition and structure of the various vegetation types that develop within the neo-valley along the transect that descends to the bank, and to report their influence. (distance in metres from the reference point at the edge of the old dam).

These data can be used to establish a pro rata of the different plant formations encountered along the transect. Although this value is thus really valid only at the transect of each station, this information can potentially constitute an approximation of the heterogeneity and distribution of vegetation at the valley scale.

This layer gives, for each riparian vegetation monitoring station and each campaign from 2021 to 2026, the following information:

– Campaign information (id, code, date, campaign),

– Station information (code, name, protocol applied, number of quadrats, code for the associated Sélune reference point and, as a result: location on the catchment area, distance to sea, distance to source and watercourse)

– Information on the transect by campaign (number and length, X, Y, LON coordinates, LAT of reference points "NGF" and end point "rive")

– Information regarding the Vegetation Units (VU) identified by campaign (number, description: code, start position, end position, EUNIS3 characteristics, 4)

– Origin of the data ("Observatoire Sélune," "Hors Observatoire Sélune," "Projet Séripage," or "Projet Restaure")

– “Point” geometry (default) corresponding to the transect reference point

– Line (alternative) geometry of the associated transect for each campaign."